In recent years there have been many advances in the production of polyolefin homopolymers and copolymers due to the introduction of single site catalysts such as metallocene catalysts. Metallo catalysts and are usually described as catalysts which are single site in nature.
The above single site catalyst systems such as metallocene complexes may be used for the polymerization of olefins in solution, slurry or gas phase. When used in the slurry or gas phase the metallocene complex and/or the activator are suitably supported. Typical supports include inorganic oxides eg. silica or polymeric supports may alternatively be used.
Examples of the preparation of supported metallocene catalysts for the polymerization of olefins may be found in WO 94/26793, WO 95/07939, WO 96/00245, WO 96/04318, WO 97/02297 and EP 642536.
The above supported polymerization c cene catalysts offer the advantage of generally a higher activity than traditional Ziegler catalyst systems may in some cases lead to certain disadvantages such as cost, instabilities as well as poor morphology of the resultant polymers as well as problems with gels and the like when subsequently transformed into films and other articles.
In recent years attempts have been made to replace the activator or cocatalyst components of the supported polymerization catalyst systems by use of activating supports.
EP 906920 describes fluorine-containing activator solid supports for metallocenes wherein the surface of the support has been modified by aluminium (or magnesium) Lewis-acid sites of formula Al—F or AlF2. The supports are prepared by a method comprising reaction of the surface —OH radicals with a functionalisation agent followed by fluorination.
WO 2005/075525 describes methods for preparing activating supports for metallocenes wherein the supports are treated with fluorinated functionalizing agents followed by heating and treatment with oxygen.
WO 2007/014889 describes similar supports prepared by functionalizing the support with an alkylating agent followed by heating under an inert gas then under oxygen and finally treatment with a fluorinating agent.
WO 2007/12465 describes fluorinated transition metal catalysts based on supports comprising bonding sequences selected from Si—O—Al—F, F—Si—O—Al, F—Si—O—Al—F.
WO 2007/131856 describes mono- or di-fluorinated metallocene catalyst components supported on fluorinated activating supports.
WO 2010/037808 describes activating supports based on perfluorinated boronic acids and aluminium alkyls and their use in the activation of metallocene complexes.
WO 2007/005676 describes activator compositions based on metal oxide supports having surface hydrogen-bonded hydroxyl groups and organoaluminium compounds having bulky functional ligands resulting in aluminate anions covalently bonded to the metal oxide via two chelating oxygen atoms.
US 2008/0319148 describes the use of halogenated alcohols or amines in the preparation of modified supports suitable for use in the polymerization of olefins.